Mr Seymour told RadioLIVE's Trudi Nelson on Sunday Mr Hipkins is going about it all wrong.

"It's one thing to disagree on whether they're good and whether they should exist, but the way he's gone about it - seeking to eradicate them, publicly write them off without even asking the question or seeking any advice about whether they work, or why the people that go to those schools want them - is just so immature.

"I suspect he's going to land himself in court before this is over. He may have been a successful student politician when he was at university, but he's now the Minister of Education with a $12 billion budget."

Charter schools are state-funded but can set their own curriculum and don't have to hire registered teachers. The Ministry of Education is presently negotiating their transition to state integration, which allows them to keep their 'special character'.

"What we're asking is they transition to a model that at least allows for their teachers to be registered, the curriculum is taught, and for them to be treated in a funding sense in the same way as state schools," Prime Minister Jacinda Ardern said earlier this month.

"The Ministry of Education will be doing the negotiating. It will be carried out in good faith."

Mr Seymour says he is yet to get a response from former US President Barack Obama after writing to him for support on the matter.